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ERK and p38 MAP kinase pathways are mediators of intestinal epithelial wound-induced signal transduction
B K Dieckgraefe1, D M Weems, S A Santoro
1Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA. dieck@im.wustl.edu
Abstract:
Repair of gastrointestinal epithelial injury involves cell migration, proliferation, and specific gene expression. The pathways responsible for epithelial wound signal transduction are poorly understood. Mechanical wounding of IEC-6 cell monolayers resulted in rapid activation of the extracellular signal-regulated kinase (ERK) and p38 MAP kinase pathways, while c-Jun amino-terminal protein kinases were not significantly activated. Two minutes after wounding cells at the wound edge strongly expressed cytoplasmic phospho-ERK. By five minutes, immunostaining was concentrated within the nucleus. Consistent with activated MAP kinase signaling cascades (which phosphorylate transcription factors implicated in immediate-early gene induction), monolayer wounding resulted in greater than 30- and 8-fold increases in c-Fos and early growth response-1 mRNA by Northern blot analysis, peaking at 20 minutes. Only slight increases in c-Jun mRNA were detected. Thus, intestinal epithelial wound signal transduction is, at least in part, mediated by activation of ERK and p38 MAP kinase signaling cascades. ERK and p38 pathways may regulate pathophysiologically relevant genes in wound repair by the induction of transcription factors.
Insights
Intestinal epithelial repair involves key signaling pathways. Mechanical wounding activates extracellular signal-regulated kinase (ERK) and p38 MAP kinase, crucial for cell repair and gene regulation.
Area of Science:
- Cell Biology
- Gastroenterology
- Molecular Biology
Background:
- Gastrointestinal epithelial repair is vital for tissue integrity.
- The specific signaling pathways governing epithelial wound healing remain largely unknown.
- Understanding these pathways is crucial for addressing gastrointestinal injury.
Purpose of the Study:
- To investigate the signal transduction pathways activated by mechanical wounding in intestinal epithelial cells.
- To identify the roles of specific mitogen-activated protein kinase (MAPK) pathways in epithelial repair.
- To elucidate the molecular mechanisms underlying intestinal epithelial wound healing.
Main Methods:
- Mechanical wounding of IEC-6 cell monolayers.
- Analysis of extracellular signal-regulated kinase (ERK) and p38 MAP kinase activation using immunostaining.
- Quantification of immediate-early gene mRNA expression (c-Fos, Egr-1, c-Jun) via Northern blot analysis.
Main Results:
- Mechanical wounding rapidly activated ERK and p38 MAP kinase pathways in intestinal epithelial cells.
- Phospho-ERK translocated from the cytoplasm to the nucleus within minutes post-wounding.
- Wounding significantly increased c-Fos and early growth response-1 (Egr-1) mRNA levels, indicating transcriptional activation.
Conclusions:
- Intestinal epithelial wound signal transduction is mediated, in part, by ERK and p38 MAP kinase activation.
- These activated pathways likely regulate genes involved in wound repair through transcription factor induction.
- The findings provide insight into the molecular mechanisms of gastrointestinal epithelial repair.